Printer with printhead close to the media

ABSTRACT

A continuous media inkjet type printer has printheads located very close to a pair of opposed media feed rollers, thereby enabling a very small printhead to media gap due to the media being held at a substantially constant location by the feed rollers.

[0001] This is a Continuation Application of U.S. Ser. No. 09/662,210filed Sep. 15, 2000

FIELD OF THE INVENTION

[0002] This invention relates to a modular printer. The inventionrelates particularly, but not necessarily exclusively, to a modularcommercial printer for effecting high speed, digital, photographicquality, commercial printing. The invention relates specifically todrying equipment for a printer for aiding drying of a printed image on aweb of print media.

BACKGROUND OF THE INVENTION

[0003] In high speed printing, large printing presses are daisy-chainedtogether to print predetermined pages of publications which are thensecured together to form the publications. Such printing presses occupyan extremely large volume and are very expensive.

[0004] The applicant has also proposed a commercial printer using anumber of floor mounted printers having pagewidth print heads. Thiscommercial printer is intended for extremely high production rates suchas up to five 180 page documents per second.

[0005] To achieve such high production rates, large quantities ofconsumables need to be readily available for the printers. Thus, onceagain, such a commercial printer needs to occupy an extremely largevolume although the cost of such a printer is considerably lower thanequivalent high end, commercial printers which do not use theapplicant's Memjet (Memjet is a trade mark of Silverbrook Research PtyLtd) technology.

[0006] The applicant has recognised a need for a commercial printerwhich occupies a smaller volume and which has a lower through put ratebut of the same quality as the applicant's previously proposed Memjetcommercial printer.

SUMMARY OF THE INVENTION

[0007] According to the invention, there is provided drying equipmentfor a printer for aiding drying of a printed image on a web of printmedia, the equipment including

[0008] a feed path through which the print media containing the printedimage is fed after printing of the image on the print media;

[0009] a drive means for driving the web through the feed path at apredetermined rate; and

[0010] a supply means in communication with the feed path for supplyingdrying fluid over at least one surface of the web.

[0011] Preferably, printing of images takes place on opposed surfaces ofthe web. Accordingly, the supply means may supply drying fluid to bepassed over both surfaces of the web.

[0012] The printer may be a pagewidth printer having an inlet, apagewidth print engine arranged proximate the inlet and an exit, thefeed path being defined as a distance between the print engine and theexit.

[0013] To aid in drying of the printed image or images, the feed pathmay have a length which is approximately 1 metre so that the surfaces ofthe web are in communication with the drying fluid for a sustainedperiod of time. It will be appreciated that the period of time for whichthe surfaces of the web are in communication with the drying fluid isalso dependent on the rate at which the web moves through the printer.

[0014] The drying means may include at least one roller set, said atleast one roller set being arranged at the inlet of the printer.Preferably, the drive means includes two roller sets, a first roller setbeing arranged at the inlet and a second roller set being arranged atthe exit of the printer.

[0015] Then, the length of the feed path may be defined as the distancebetween the print engine and a centre line of the second roller set.

[0016] The drive means may be operable to drive the web through the feedpath at a rate of from about 0.5 m/s to about 2 m/s. More particularly,if six “color” printing is being effected, the web may move at a rate ofabout 1.6 m/s and, if twelve “color” printing is being effected, the webmay move through the printer at a rate of approximately 0.8 m/s. Theterm “color” in this specification includes different colored inksvisible in the visible spectrum as well as ink which is invisible in thevisible spectrum but visible only in the infrared spectrum, an inkfixative and a print media surface varnish.

[0017] The fixative may be used to fix the inks on the surface of theprint media and may further facilitate drying of the ink on the printmedia.

[0018] The supply means may include a supply duct arranged alongside thefeed path, the supply duct including a connection means for connectionto a source of the drying fluid.

[0019] The duct may have a length approximating that of the feed path.The duct may have outlet openings which direct drying fluid transverselyto a direction of movement of the web along the feed path.

[0020] The duct may be arranged alongside an inner surface of one of theside walls of the printer. Then, an opposed side wall of the printer mayinclude vents through which drying fluid may be exhausted from aninterior of the printer.

[0021] Accordingly, by having a feed path of approximately 1 metre andfeeding the web at the desired rate through the feed path, drying ofimages printed on the web is facilitated. By having the images dried inthis manner, high speed printing is facilitated.

[0022] In another broad form the invention provides a pagewidthprinthead assembly including;

[0023] a first printhead including at least two printhead 0 modules;

[0024] a controller module associated with each of the printheadmodules, each controller assembly including memory and a print enginecontroller that controls the respective printhead module;

[0025] The assembly may include a second printhead substantiallyidentical to the first printhead.

[0026] When the assembly includes a second printhead, preferably eachcontroller module controls a printhead module of the first printhead anda printhead module of the second printhead.

[0027] The at least two printhead modules are preferably arranged end onend.

[0028] The controller modules are preferably arranged end on end.

[0029] Preferably each controller module includes a discrete circuitboard, each circuit board having a data connector for connection to thecircuit board of an adjacent controller module.

[0030] Each controller module may have two data connectors, each forconnection to another controller module. Preferably each data connectoris located at opposed ends of each controller module.

[0031] The printhead modules of the first printhead are preferablymounted on a first housing.

[0032] The printhead modules of the second printhead are preferablymounted on a second housing.

[0033] In another broad form the invention provides a housing for aninkjet type printhead, the housing including;

[0034] at least one mounting for at least one printhead chip;

[0035] at least one fluid passageway having at least two fluid inletsand at least one outlet that, in use, communicate with at least oneprinthead chip.

[0036] In another broad form the invention provides a printhead assemblyfor an inkjet type printer, the assembly including;

[0037] a housing;

[0038] a plurality of printhead chips mounted on or in the housing;

[0039] the housing including at least one passageway in fluidcommunication with at least one printhead chip;

[0040] each respective at least one passageway having at least two fluidinlets.

[0041] The housing is preferably elongate with a plurality of mountingsextending end-on-end along the length of the housing. More preferablythe housing is symmetric in at least one view.

[0042] Preferably each fluid passageway has two fluid inlets.

[0043] In preferred forms the housing is elongate and each fluidpassageway has two fluid inlets, each at opposite ends of the housing.

[0044] The assembly may include at least one closure sealing closing atleast one of said at least two fluid inlets.

[0045] In another broad form the invention provides a printer includinga printhead assembly having a fluid passageway in communication with aprinthead chip, the fluid passageway having two inlets, a first inletconnected to a source of fluid to be printhead by the printhead chip anda second inlet closed by a closure.

[0046] In another broad form the invention provides a method of aidingdrying of printed material in a continuous media inkjet type printer,the method including substantially simultaneously printing at least oneink and at least one drying agent onto the media, the at least onedrying agent reducing the drying time of at least one of the at leastone ink on the media compared to when printed without the drying agent.

[0047] The at least one drying agent is preferably a fixative for atleast one of the at least one ink.

[0048] The at least one ink may include a varnish.

[0049] The method may include providing a first printhead, that printsat least one of the at least one ink, and a second printhead, thatprints at least one of the at least one drying agent, adjacent to thefirst printhead, one of the first and second printheads being locateddownstream of the other printhead.

[0050] The second printhead is preferably located downstream of thefirst printhead.

[0051] The method may include printing on both surfaces of thecontinuous print media.

[0052] The at least one drying agent preferably facilitates drying inwarm air.

[0053] In another broad from the invention provides an inkjet typeprinter including:

[0054] a printer mechanism that prints at least one material on at leastone surface of print media;

[0055] a media conveyor that engages the media to convey the media pastthe printer mechanism, said media conveyor including at least onecomponent that engages the media downstream of the printer mechanism,the at least one component located at a distance from the printermechanism, and the conveyor operated to convey said media past theprinter mechanism, such that material printed by the printer mechanismonto the media is dry or substantially dry when it reaches the at leastone component.

[0056] Preferably the conveyor operates to convey the media past theprinter mechanism at between about 0.5 m/s and about 2 m/s.

[0057] In some embodiments the printer of claim 2 wherein the conveyormay operates to convey the media past the printer mechanism at about 1.6m/s.

[0058] In other embodiments the conveyor operates to convey the mediapast the printer mechanism at about 0.8 m/s.

[0059] In some embodiments the conveyor is operated to convey the mediapast the printer mechanism at a speed such that the media takes betweenabout 0.5 seconds and about 2 seconds to travel from the printermechanism to the at least one component.

[0060] In some embodiments wherein the conveyor is operated to conveythe media past the printer mechanism at a speed such that the mediatakes between about 0.5 seconds and about 1.25 seconds to travel fromthe printer mechanism to the at least one component.

[0061] In other embodiments the conveyor is operated to convey the mediapast the printer mechanism at a speed such that the media takes betweenabout 0.5 seconds and about 0.625 seconds to travel from the printermechanism to the at least one component.

[0062] In other embodiments the conveyor is operated to convey the mediapast the printer mechanism at a speed such that the media takes betweenabout 0.5 seconds and about 1 second to travel from the printermechanism to the feed mechanism.

[0063] In some embodiments the media travels along a path about 1 m inlength between the printer mechanism and the at least one component.

[0064] In preferred embodiments the print media is continuous.

[0065] In another broad form the invention provides a printhead assemblyincluding:

[0066] a housing;

[0067] at least one multi-fluid inkjet printhead chip;

[0068] the housing defining a plurality of fluid galleries, each ofwhich is isolated from the other galleries;

[0069] each gallery being in fluid communication with said at least oneprinthead chip.

[0070] The preferably, in cross-section, the galleries follow anon-linear path and more preferably a J-shaped path galleries may belocated one on top of each other above the at least one printhead chip.

[0071] The in cross-section, the galleries are preferably arranged on anon-linear path.

[0072] The in cross-section, the galleries are preferably arranged alonga J-shaped path.

[0073] The housing preferably includes an arcuate shaped section.

[0074] Each gallery preferably has at least two fluid inlets, wherebyfluid may be supplied to each gallery from one or more of said fluidinlets.

[0075] The printhead assembly may be an elongate pagewidth printheadassembly and said at least two fluid inlets comprise inlets at eitherlongitudinal end of the housing.

[0076] The printhead assembly may also include at least one closureclosing at least one inlet of each gallery.

[0077] In another broad form the invention provides a printer includinga printhead assembly the assembly including:

[0078] a housing;

[0079] at least one multi fluid inkjet printhead chip mounted on or inthe housing;

[0080] the housing defining a plurality of fluid galleries, each ofwhich is isolated from the other galleries;

[0081] each gallery being in fluid communication with said at least oneprinthead chip.

[0082] The arcuate shaped section preferably has a centre of curvaturecoincident with the axis.

[0083] The printer may include at least one print media feed rollermounted for rotation about an axis, said printhead assembly beinglocated adjacent the roller with the arcuate shaped section adjacent theroller.

[0084] The printer may also include at least one closure closing atleast one inlet of each gallery.

[0085] In another broad form the invention provides a pagewidthprinthead assembly including:

[0086] a longitudinal housing;

[0087] at least one elongate printhead chip mounted in or on the housingand extending along the length of the housing;

[0088] at least one gas supply duct in the housing that supplies gas tothe at least one printhead chip, said duct extending along thelongitudinal direction of the housing.

[0089] Preferably the at least one printhead chip includes a pluralityof printhead chips extending end on end along the length the housing.

[0090] The housing preferably has first and second ends and the at leastone gas supply duct is open at one of the first and second ends.

[0091] The housing preferably has first and second ends and the at leastone gas supply duct is open at both the first and second ends. Theassembly may include at least one closure that engages the at least onegas supply duct at one of the first and second ends. The assembly mayinclude a gas supply connector that connects to the at least one duct atthe other of the first and second ends.

[0092] There may be only a single gas supply duct.

[0093] The at least one gas supply duct may be located to one side ofthe at least one printhead chip.

[0094] In another broad form the invention provides an inkjet printerhaving:

[0095] a first set of opposed rollers that engage opposite sides ofprint media located there between;

[0096] a second set of opposed rollers that engage opposite sides ofprint media located there between,

[0097] an inkjet type printing mechanism that prints ink on at least onesurface of the media from

[0098] at least one nozzle, said printing mechanism being locatedbetween the two pairs of rollers,

[0099] said at least one nozzle being approximately 0.75 mm from therespective media surface.

[0100] Preferably the media travels from the first set to the second ofrollers.

[0101] At least one of the first set of rollers may have a effectiveoutside radius of R₁, and preferably said printing mechanism printsmaterial onto the at least one surface within 2R₁, of the line ofengagement of the rollers with the media and more preferably within R₁of the line of engagement.

[0102] The printing mechanism prints material onto the media within R₁of the line of engagement.

[0103] The media is preferably maintained in tension between the twosets of rollers.

[0104] The printing mechanism preferably includes a first print enginethat prints on one surface of the print media and a second print enginethat prints on the other surface of the print media.

[0105] The printing mechanism preferably includes a printhead thatextends transversely across the media, said printhead mounted on amovable support, whereby the printhead is movable toward or away fromthe surface the media.

[0106] The media is preferably continuous.

[0107] Preferably both rollers of the first set of the first set have aneffective outside radius of R₁.

[0108] Preferably the printing mechanism prints material onto bothsurfaces of the media.

[0109] In another broad form the invention provides an inkjet typeprinter including:

[0110] a print media feed mechanism including a first roller thatengages print media and is rotatable about an axis to move the printmedia along a path;

[0111] a first printing mechanism that prints one or more materials ontoa first surface of the print media;

[0112] the first printing mechanism located adjacent the first roller toprint at least some of the one or more materials onto the print medialess than 2R₁ from a first line of contact of the first roller with theprint media, where R₁ is the effective outside radius of the firstroller.

[0113] Preferably the first printing mechanism is located to print atleast some materials onto the print media less than R₁ from the first ofcontact.

[0114] The first roller may be located upstream of the printingmechanism.

[0115] The printing mechanism and the first roller are preferablylocated on the same side of the print media.

[0116] The first printing mechanism may include a first printhead, thefirst printhead located to print material within R₁ of the first line ofcontact.

[0117] The first printing mechanism may include a second printhead thesecond printhead, located to print material within 2R₁, of the firstline of contact.

[0118] The printer may include a second roller opposed to the firstroller and located on an opposite side of the print media to the firstroller, said second roller engaging the print media.

[0119] The printer may include a second printing mechanism that printsone or more materials onto a second surface of the print media;

[0120] the second printing mechanism printing at least some of the oneor more materials onto the print media less than about 2R₂ from a secondline of contact of the second roller with the print media, where R₂ isthe effective outside radius of the second roller.

[0121] Preferably the second printing mechanism is located to print atleast some material onto the print media less than R₂ from the secondline of contact.

[0122] The second printing mechanism may include a third printhead thatis located to print material within R₂ of the second line of contact.

[0123] The second printing mechanism may include a fourth printhead thatis located to print material within 2R₂ of the second line of contact.

[0124] The first printing mechanism is preferably located to print atleast some material onto the print media within about 1 cm of the lineof contact.

[0125] The second printing mechanism is preferably located to print atleast some material within about 1 cm of the second line of contact.

[0126] The print media to first printing mechanism separation ispreferably about 0.75 mm.

[0127] The print media to second printing mechanism separation ispreferably about 0.75 mm.

[0128] In another broad from the invention provides a printer including:

[0129] a printing mechanism that prints one or more materials onto atleast one surface of print media;

[0130] a conveyor that conveys the print media from the print mechanismalong a path;

[0131] at least one fluid outlet adjacent the path that outputs dryingfluid over at least the at least one surface of the print media that hasbeen printed on by the printing mechanism.

[0132] The drying fluid preferably moves transversely across the printmedia relative to the general direction of travel of the print media.

[0133] The at least one fluid outlet may be located to one side of thepath.

[0134] The drying fluid may pass over both surfaces of the print media.

[0135] The print media is preferably conveyed along the path at asubstantially constant speed.

[0136] The print media may be continuous.

[0137] The drying fluid is preferably air and more preferably warmedair.

[0138] The printer preferably includes an enclosure substantiallyenclosing the path, said at least one fluid outlet being located withinthe enclosure.

[0139] There is preferably at least one vent in the enclosure throughwhich drying fluid may escape the enclosure.

[0140] The printing mechanism may include at least one stationary inkjetprinthead assembly extending across substantially the width of the printmedia.

[0141] The printing mechanism may include at least one stationary inkjetprinthead assembly extending across substantially the width of eachopposed surface of the print media.

[0142] In another broad form the invention provides an inkjet typeprinter including:

[0143] a conveyor that conveys media along a path past at least oneprinthead assembly that extends substantially across the width of themedia relative to the direction of travel along the path;

[0144] a control system that controls the printhead assembly;

[0145] a buffer in which print data is stored,

[0146] said control system reading print data from said buffer andcausing said at least one printhead assembly to print informationderived from the read print data onto the media.

[0147] Preferably the buffer stores print data corresponding to at leastone page of information.

[0148] The print data is preferably received by the printer via at leastone input is stored in the buffer whilst simultaneously the controlsystem reads print data stored in the buffer. The conveyor preferablyconveys the media past the at least one printhead assembly at asubstantially constant speed.

[0149] Preferably the media is continuous and preferably the buffer issized to allow continuous printing.

[0150] Each printhead assembly may include at least two printheadmodules arranged end on the end across the width of the media.

[0151] The buffer may include at least two physically and logicallydistinct memory modules.

[0152] The control system may include at least two physically andlogically distinct control modules.

[0153] The printer may have a printable width comprised of at least twosections and

[0154] each respective printhead assembly includes at least twoprinthead modules each of which prints a different section;

[0155] said the buffer includes at least one logically distinct memorymodule associated with each printhead module, and

[0156] said control system includes at least one physically andlogically distinct control module associated with each printhead module,

[0157] and wherein the each control module retrieves data from anassociated memory module and causes the associated printhead module toprint information corresponding to data so retrieved.

[0158] Each printhead module may include two elongate printhead chipsassemblies, each of said printhead chip assemblies extending in parallelacross the respective section. Preferably each control module includestwo printer engine control chips. The printer preferably includes atleast one data input and a serial data connection interconnecting saidbuffer with said at least one input. More preferably there are two datainputs.

[0159] The printer may have a printable width of about 18.625 inches,with each printhead assembly capable of printing 12 different materialsand a buffer of about 32 MB per printable surface. This equates to abuffer size of about 5772 bytes per colour per cm of printable width.

[0160] Greater buffer sizes, up to about 2 GB per printable surface maybe provided.

[0161] In another broad form the invention provides an inkjet typeprinter including:

[0162] a conveyor that conveys media along a path past at least oneprinthead assembly that extends substantially across the width of themedia relative to the direction of travel along the path;

[0163] a control system that controls the printhead assembly;

[0164] a buffer in which print data is stored,

[0165] said control system reading print data from said buffer andcausing said at least one printhead assembly to print informationderived from the read print data onto the media.

[0166] Preferably the buffer stores print data corresponding to at leastone page of information.

[0167] The print data is preferably received by the printer via at leastone input is stored in the buffer whilst simultaneously the controlsystem reads print data stored in the buffer.

[0168] The conveyor preferably conveys the media past the at least oneprinthead assembly at a substantially constant speed.

[0169] Preferably the media is continuous and preferably the buffer issized to allow continuous printing.

[0170] Each printhead assembly may include at least two printheadmodules arranged end on the end across the width of the media.

[0171] The buffer may include at least two physically and logicallydistinct memory modules.

[0172] The control system may include at least two physically andlogically distinct control modules.

[0173] The printer may have a printable width comprised of at least twosections and

[0174] each respective printhead assembly includes at least twoprinthead modules each of which prints a different section;

[0175] said the buffer includes at least one logically distinct memorymodule associated with each printhead module, and

[0176] said control system includes at least one physically andlogically distinct control module associated with each printhead module,

[0177] and wherein the each control module retrieves data from anassociated memory module and causes the associated printhead module toprint information corresponding to data so retrieved.

[0178] Each printhead module may include two elongate printhead chipsassemblies, each of said printhead chip assemblies extending in parallelacross the respective section.

[0179] Preferably each control module includes two printer enginecontrol chips.

[0180] The printer preferably includes at least one data input and aserial data connection interconnecting said buffer with said at leastone input. More preferably there are two data inputs.

[0181] The printer may have a printable width of about 18.625 inches,with each printhead assembly capable of printing 12 different materialsand a buffer of about 32 MB per printable surface. This equates to abuffer size of about 5772 bytes per colour per cm of printable width.

[0182] Greater buffer sizes, up to about 2 GB per printable surface maybe provided.

[0183] In another broad form the invention provides an inkjet typeprinter including:

[0184] a conveyor that conveys media along a path, past at least oneprinthead assembly that extends substantially across the width of themedia relative to the direction of travel along the path;

[0185] a control system that controls the printhead assembly;

[0186] at least one input that receives document data;

[0187] a buffer in which document data received via the at least oneinput is stored,

[0188] said control system reading document data from said buffer andcausing said at least one printhead assembly to print at least onedocument derived from the document data onto the media,

[0189] wherein the printer prints at least one document corresponding tofirst document data stored in the buffer whilst simultaneouslyreceiving, via the at least one input, and storing, in the buffer,second document data.

[0190] The buffer preferably stores more than two sets of document datafor each surface that is printed on.

[0191] Preferably the printer includes at least one printhead assemblythat prints on one surface of the media and at least one printheadassembly that prints on a second surface of the media.

[0192] The conveyor preferably conveys the media past the at least oneprinthead assembly at a substantially constant speed.

[0193] Preferably the media is continuous and preferably the buffer issized to allow continuous printing.

[0194] Each printhead assembly may include at least two printheadmodules arranged end on the end across the width of the media.

[0195] The buffer may include at least two physically and logicallydistinct memory modules.

[0196] The control system may include at least two physically andlogically distinct control modules.

[0197] The printer may have a printable width comprised of at least twosections and

[0198] each respective printhead assembly includes at least twoprinthead modules each of which prints a different section;

[0199] said the buffer includes at least one logically distinct memorymodule associated with each printhead module, and

[0200] said control system includes at least one physically andlogically distinct control module associated with each printhead module,

[0201] and wherein the each control module retrieves data from anassociated memory module and causes the associated printhead module toprint information corresponding to data so retrieved.

[0202] Each printhead module may include two elongate printhead chipsassemblies, each of said printhead chip assemblies extending in parallelacross the respective section.

[0203] Preferably each control module includes two printer enginecontrol chips.

[0204] The printer preferably includes a serial data connectioninterconnecting said buffer with said at least one input. Morepreferably there are two data inputs.

[0205] The printer may have a printable width of about 18.625 inches,with each printhead assembly capable of printing 12 different materialsand a buffer of about 32 MB per printable surface. This equates to abuffer size of about 5772 bytes per color per cm of printable width.

[0206] Greater buffer sizes, up to about 2 GB per printable surface maybe provided.

BRIEF DESCRIPTION OF THE DRAWINGS

[0207] The invention is now described by way of example with referenceto the accompanying drawings in which:

[0208]FIG. 1 shows a three dimensional view of a printer, in accordancewith the invention;

[0209]FIG. 2 shows a plan view of the printer;

[0210]FIG. 3 shows a side view of the printer;

[0211]FIG. 4 shows an end view of the printer;

[0212]FIG. 5 shows a three dimensional view of a printer stack, inaccordance with one embodiment of the invention;

[0213]FIG. 6 shows a three dimensional view of a printer stack, inaccordance with another embodiment of the invention;

[0214]FIG. 7 shows a three dimensional view of the printer including itsfluid connections;

[0215]FIG. 8 shows a detailed, three dimensional view of part of theprinter;

[0216]FIG. 9 shows a three dimensional, exploded view of the printer;

[0217]FIG. 10 shows a three dimensional view of a print engine of theprinter;

[0218]FIG. 11 shows a sectional end view of the print engine;

[0219]FIG. 12 shows, on an enlarged scale, part of the print engine;

[0220]FIG. 13 shows a three dimensional view of one of the print headassemblies of the print engine;

[0221]FIG. 14 shows a three dimensional, exploded view of one of theprint head assemblies;

[0222]FIG. 15 shows a sectional side view of a print media loadingmechanism of the printer, in its loading configuration;

[0223]FIG. 16 shows a sectional side view of the loading mechanism ofthe printer in its open, non-loading configuration;

[0224]FIG. 17 shows a three dimensional view of the loading mechanism inits non-loading configuration; and

[0225]FIG. 18 shows a three dimensional, exploded view of the loadingmechanism in its loading configuration.

DETAILED DESCRIPTION OF THE DRAWINGS

[0226] Referring to the drawings, reference numeral 10 generallydesignates a printer, in accordance with the invention. The printer 10is a modular printer to be used in combination with other, identicalprinters, as will be described in greater detail below for effectinghigh speed, digital, photographic quality, commercial printing. Arraysof the printers 10 can be combined to provide scalable printing systems.However, single printers 10 may also be used individually, if desired.

[0227] The printer 10 comprises a housing 12. The housing 12 is made upof an upper cover 14, a lower cover 16 (FIG. 9), a first side wall 18and a second, opposed side wall 20 (FIG. 9). Each side wall 18, 20terminates in an end cap or cheek molding 22. Each cheek molding 22 isthe same to reduce the costs of production of the printer 10. Each cheekmolding 22 has a slot in which an application-specific insert 24 isreceived.

[0228] The housing 12 surrounds a frame 26. Internal components of theprinter 10 are supported on the frame 26.

[0229] Opposed cheek moldings 22 at each end of the housing 12 support aguide roller 28 adjustably between them. Thus, each cheek molding 22defines an arcuate slot 30 within which an axle of its associated roller28 is received.

[0230] As described above, it is intended that, for commercial printingapplications, a plurality of the printers 10 will be used together. Asillustrated in FIGS. 5 and 6 of the drawings, the printers 10 arestacked together to form a stack 40. In the embodiment illustrated atFIG. 5, the stack 40 is arranged on a support table 42. A lowermostprinter 10 in the stack 40 is locked to the table 42 by means of lockingfeet 44 of the printer 10. The locking feet 44 of each subsequentprinter 10 in the stack 40 are received in associated holes 46 in a topof a subjacent printer 10. Each locking foot 44 has a bayonet fitting sothat, when the foot 44 is inserted into one of the holes 46 of thesubjacent printer or the table 42, as the case may be, a quarter turn ofthe foot 44 locks the upper printer 10 with respect to the subjacentprinter 10 or the table 42.

[0231] As illustrated in FIG. 5 of the drawings, the printers 10, whenstacked horizontally, may be offset with respect to each other bylocking the locking feet 44 of one printer 10 into the appropriate holes46 of the subjacent printer. Hence, a plurality of serially alignedholes 46 is arranged adjacent each cheek molding 22. By appropriateselection of the holes 46, the requisite degree of offset, if any, canbe achieved.

[0232] The offset stacking of the printers 10 allows print media, suchas paper 48, to be fed from unwinders (not shown) into each of theprinters 10 at a predetermined angle and to be fed out of the printers10 at a suitable exit angle. If the paper 48 is to be fed in and out ofthe printers 10 horizontally, the printers 10 of the stack 40 arevertically aligned with respect to each other.

[0233] In FIG. 6, another embodiment of the stack 40 is shown. In thisembodiment, the printers 10 are arranged vertically and are spacedhorizontally with respect to each other. In the example illustrated,paper 48 is fed into each printer 10 at an upper end of the printer andis fed out, after printing, through a bottom of each printer 10. Thestack 40 is supported on a framework 49 with the printer at one end ofthe stack 40 being locked to an end plate 51 of the framework 49 via itslocking feet 44. Adjacent printers 10 in the stack 40 are lockedtogether by inserting the locking feet 44 of one printer 10 into theappropriate holes 46 of the adjacent printer 10. A control console 54 isprovided for controlling operation of the printer stack 40.

[0234] Each printer 10 communicates with its controller and with otherprinters in the stack 40 via a USB2 connection 50 received in a doubleUSB port arrangement 52. The port arrangement 52 has an inlet port andan outlet port for enabling the printers 10 of the stack 40 to bedaisy-chained together and to communicate with each other.

[0235] Each printer includes a print engine 56 made up of a pair ofopposed print head assemblies 54 for enabling double-sided printing tobe effected. The print head assembly 54 (FIG. 11) of the print engine 56of the printer 10 can print in up to twelve colors. As will be describedin greater detail below, each print head assembly 54 is a duplexed printhead so that, if desired, six colors, duplicated, can be printed by eachprint head assembly 54. Ink is fed to the print engine 56 via an inkcoupling box 58. The coupling box 58 supports twelve ink couplings 60thereon. Ink hoses 64 are coupled to the coupling box 58 via thecouplings 60 and communicate with the print head assemblies 54 of theprint engine 56 via an ink connector 62 (FIG. 9). A power connectionport 66 is also supported on the ink coupling. The port 66 is receivedthrough an opening 68 in one of the inserts 24 of one of the cheekmoldings 22. The same insert 24 supports an air coupling 70. An air hose72 (FIG. 7) feeds air to the print head assemblies 54 of the printengine 56 to maintain print head nozzles (not shown) of the print headassemblies 54 free of debris and foreign matter.

[0236] A roller assembly 74 is mounted at an inlet end of the printer10. The roller assembly 74 includes a drive roller 76 and a drivenroller 78. The drive roller 76 is driven by a drive motor 80 supportedon a metal bracket 82. The metal bracket 82 is mirrored by acorresponding bracket 84 at an opposed end of the roller assembly 74.The brackets 82 and 84 are supported on the frame 26.

[0237] In addition, a similar, exit roller assembly 86 is provided at anoutlet end of the printer 10. Once again, the roller assembly 86 has adrive roller 88 driven by a drive motor 90 and a driven roller 92. Therollers 86 and 92 are supported between metal brackets 94 and 96. Thebrackets 94 and 96 are secured to the frame 26. The bracket 94 alsosupports the motor 90.

[0238] The drive roller 76 drives the driven roller 78 via a set ofhelical gears 132. A similar arrangement applies in respect of theroller 88 and 92 of the roller assembly 86.

[0239] The cheek molding 22, at the inlet end of the printer 10,opposite the molding 22 supporting the air coupling 70, also supports aUSB control PCB 98.

[0240] The print engine 56 is supported by a chassis comprising a pairof opposed metal brackets 100, 102 mounted downstream (in a direction offeed of the paper) of the roller assembly 74. Each metal bracket 100,102 supports one of the print head assemblies 54 of the print engine 56.

[0241] The print engine 56 is shown in greater detail in FIGS. 10 to 12of the drawings. As described above, the print engine 56 comprises twoprint head assemblies 54. The print head assemblies 54 are arranged inopposed relationship to enable double sided printing to be effected. Inother words, the paper 48 passes between the print head assemblies 54.The brackets 100, 102 support the print head assemblies 54 and positionthe print head assemblies 54 approximately 0.75 mm apart from the web ofpaper 48. This distance is automatically adjusted by the brackets 100,102 to maintain constant spacing with varying paper thickness.

[0242] In addition, as will be described in greater detail below, printheads of the print head assemblies 54 are so designed as to allow forclose proximity to the rollers 76 and 78 resulting in a closelycontrolled paper to print head gap.

[0243] Each print head assembly 54 comprises a first print head 104 anda second, adjacent print head 106. Each print head 104, 106, further, ismade up of two modules 104.1 and 104.2 and 106.1 and 106.2,respectively.

[0244] The modules 104.1 and 106.1 are coupled together and arecontrolled by a first printed circuit board (PCB) 108. Similarly, themodules 104.2 and 106.2 are coupled together and are controlled by asecond printed circuit board (PCB) 110. PCB's 108 and 110 communicatewith print head chips 112 of the print heads 104 and 106 via flex PCB's114. These flex PCB's 114 terminate in terminal pads 116 on moldings 118of the modules 104.1, 104.2, 106.1 and 106.2 of the print heads 104 and106. The terminal pads 116 communicate with corresponding pads (notshown) of the PCB's 108, 110.

[0245] It is to be noted that the moldings 118 are mirror images of eachother, each having ink inlets 120 at a free end thereof. Ink is fed inat one end of interconnected moldings 118 only so that the inlets 120not being used are plugged by appropriate plugs. Also, the PCB's 108,110 are mirror images of each other. This reduces the cost of productionof the printer 10 and also enables rapid and easy assembly of theprinter 10. The PCB's 108 and 110 communicate with each other via aserial cable 122. One of the PCB's 108, 110 is connected via a connector124 to the USB circuit board 98.

[0246] Each PCB 108, 110 includes two print engine controllers (PEC's)126 and associated memory devices 128. The memory devices 128 aredynamic random access memory (DRAM) devices.

[0247] The molding 118 of each print head assembly 54 is supported onthe frame 100, 102 via an end plate 130 (FIG. 13).

[0248] The print engine 56 is shown in greater detail in FIG. 11 of thedrawings. The print engine 56 comprises the two print head assemblies54. As previously described, each print head assembly 54 comprises twoprint heads 104, 106. Each print head 104, 106 has a print head chip 112associated therewith. The print head chips 112 of the print heads 104,106 are supported along a longitudinal edge portion of the moldings 118.The edge portion of each molding 118 which carries the print head chip112 is arcuate. The arcuate portion of each molding 118 has a radius ofcurvature which approximates that of the radius of the rollers 76, 78.This design of the print heads 104, 106 allows for close proximity ofthe print head chips 112 to the rollers 76, 78 resulting in a closelycontrolled paper to print head gap. In so doing the printhead chip 112prints in a portion of the paper, which is taut, resulting in a moreaccurate deposition of ink drops on the paper 48.

[0249] As illustrated more clearly in FIG. 12 of the drawings, an airchannel 138 is arranged adjacent each print head chip 112 for feedingair to the print head chip 112 from the air hose 72.

[0250] With this arrangement of print head assemblies 54, either sixcolors or twelve colors can be printed. Where six colors are to beprinted, these are duplicated in the print heads 104, 106 of eachassembly 54 by having the appropriate colored ink or related matter(referred to for convenience as “colors”) in the relevant galleries 136of the moldings 118. Instead, each print head assembly 54 can print thetwelve “colors” having the appropriate “colors” charged into thegalleries 136 of the print heads 104, 106. Where six “colors” are to beprinted, these are normally cyan, magenta, yellow and black. Theremaining galleries 136 then have an ink fixative and a varnish. Wheretwelve “colors” are to be printed, the “colors” are cyan, magenta,yellow, black, red, green, blue, either three spot colors or two spotcolors and infrared ink, and the fixative and the varnish.

[0251] The printer 10 is designed so that, where six “colors” are to beprinted, the printer can print at a printing speed of up to 1,360 pagesper minute at a paper speed of 1.6 m/s. Where twelve “colors” are to beprinted, the printer 10 is designed to operate at a printing speed of upto 680 pages per minute at a paper speed of 0.8 m/s.

[0252] The high speed is achieved by operating the nozzles of the printhead chips 112 at a speed of 50,000 drops per second.

[0253] Each print head module 104.1, 104.2, 106.1, 106.2 has six nozzlerows per print head chip 112 and each print head chip 112 comprises92,160 nozzles to provide 737,280 nozzles per printer. It will beappreciated that, with this number of nozzles, full 1600 dpi resolutioncan be achieved on a web width of 18.625 inches. The provision of a webwidth of this dimension allows a number of pages of a document to beprinted side-by-side.

[0254] In addition, matter to be printed is locally buffered and, as aresult, complex documents can be printed entirely from the locallybuffered data.

[0255] It is also intended that the amount of memory 128 installed oneach board 108, 110 is application dependent. If the printers 10 arebeing used for unchanging pages, for example, for offset pressreplacement, then 16 megabytes per memory module is sufficient. If theamount of variability on each page is limited to text, or a small rangeof variable images, then 16 megabytes is also adequate. However, forapplications where successive pages are entirely different, up to 1gigabyte may need to be installed on each board 108, 110 to give a totalof 4 gigabytes for the print engine 56. This allows around 2,000completely different pages to be stored digitally in the print engine56. The local buffering of the data also facilitates high speed printingby the printers 10.

[0256] The spacing between the print engine 56 and the exit rollerassembly 86 is approximately one metre to allow for a one secondwarm-set ink drying time at a web speed of the paper 48 of approximately0.8 metres per second. To facilitate drying of the printed images on thepaper 48 the fixative is used in one of the ink galleries 136. Inaddition, warm air is blown into the interior of the printer 10 from asource (not shown) connected to an air inlet 140 (FIG. 1) via an airhose 142. The air inlet communicates with a metal air duct 144 (FIG. 9)which blows the warm air over the paper 48 exiting the print engine 56.Warm air is exhausted from the interior of the printer by means of vents146 in the side wall 20 of the housing 12 of the printer 10.

[0257] The printer 10 includes a print media loading mechanism 150 forloading the paper 48 into the interior of the printer 10. The loadingmechanism 150, comprises a pair of opposed endless belts 152 (shown moreclearly in FIGS. 15 to 18 of the drawings). Although not illustrated assuch, these belts 152 are foraminous to enable the warm air ducted inthrough the duct 144 to be blown through the belts 152 over bothsurfaces of the paper 48, after printing, in use.

[0258] Each belt 152 passes around a pair of spaced rollers 154. Therollers 154 are held captive to be vertically slidable in slides 156.The slides 156 are mounted on the frame 26 of the printer 10.

[0259] Each roller 154 is mounted at one end of an arm 158. The opposedend of each arm 158 is connected at a common pivot point 160 to atraverser block 162 so that the arms 158 are connected to theirassociated traverser block 162 scissors-fashion. The traverser block 162is, in turn, mounted on a lead or worm screw 164. The worm screw 164 isrotatably driven by a motor 166 supported on a bracket 168.

[0260] The rollers 154 are driven by a motor 170 (FIG. 18).

[0261] When it is desired to load paper 48 into the printer 10, themechanism 150 is operated by a paper load button 172 (FIGS. 1 and 8).This causes the roller motor 170 to be activated as well as the motor166. Rotation of the motor 166 causes the traverser blocks 162 to movein the direction of arrows 174 to bring the belts 152 into abutment witheach other. A leading edge of the paper 48 is fed between the belts 152,is grabbed by the belts 152 and is fed through the printer 10 to exitthrough the exit roller assembly 86. Once the paper 48 has been loaded,the direction of the motor 166 is reversed so that the traverser blocksmove in directions opposite to that of arrows 174 causing the belts 152to move to the position shown in FIG. 16 of the drawings. Thus, duringprinting, the belts 152 are spaced from, and do not bear against,surfaces of the paper 48.

[0262] Accordingly, by means of the invention, a modular printer whichcan print at commercial printing speeds is provided for the printing ofdocuments. Several modules can be arrayed in combination with insertingmachines for published documents, such as magazines, with variable paperweights. In addition, print module redundancy allows paper splicing on astopped web with no down time as the other printer modules in the stack40 take up printing of the pages which would normally be printed by theout of operation printer 10.

[0263] Each printer 10 is provided with its document printingrequirements over the USB2 communications network (or optional Ethernet)from a work station such as the console 54.

[0264] Also, due to memory capacity of each printer 10, tens ofthousands of images and text blocks can be stored in memory allowingcompletely arbitrary selections on a page by page basis. This allows theprinting of matter such as catalogues and magazines which are highlycustomised for each reader.

[0265] It will be appreciated by persons skilled in the art thatnumerous variations and/or modifications may be made to the invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects as illustrative and notrestrictive.

1. An inkjet printer having: a first set of opposed rollers that engage opposite sides of print media located there between; a second set of opposed rollers that engage opposite sides of print media located there between, an inkjet type printing mechanism that prints ink on at least one surface of the media from at least one nozzle, said printing mechanism being located between the two pairs of rollers, said at least one nozzle being between 0.5 mm and 3 mm from the respective media surface.
 2. The printer of claim 1 wherein the media travels from the first set to the second of rollers.
 3. The printer of claim 1 wherein at least one of the first set of rollers has a effective outside radius of R₁, and said printing mechanism prints material onto the at least one surface within 2R₁, of the line of engagement of the rollers with the media.
 4. The printer of claim 3 wherein the printing mechanism prints material onto the media within R₁ of the line of engagement.
 5. The printer of claim 1 wherein the media is maintained in tension between the two sets of rollers.
 6. The printer of claim 1 wherein the printing mechanism includes a first print engine that prints on one surface of the continuous print media and a second print engine that prints on the other surface of the continuous print media.
 7. The printer of claim 1 wherein the printing mechanism includes a printhead that extends transversely across the media, said printhead mounted on a movable support, whereby the printhead is movable toward or away from the surface the media.
 8. The printer of claim 1 wherein the media is continuous.
 9. The printer of claim 1 wherein both rollers of the first set have an effective outside radius of R₁.
 10. The printer of claim 1 wherein the printing mechanism prints material onto both surfaces of the media. 